The invention discloses a preparation method of a nano silicon dioxide/ferroferric oxide magnetic radiographic particle enhanced biological magnesium-based composite material and relates to a preparation method of a magnesium-based composite material. The preparation method solves the technical problem that an existing biomedical magnesium-based composite material is relatively poor in targeting and positioning ability and low in forming ability. The preparation method comprises the following steps: I, preparing a nano magnetic radiographic particle coalition; and II, carrying out ultrasonic coupling, stirring and self-regulating treatment and graded temperature-changing infiltrating and hot press molding. The interfacial activity of nano silicon dioxide hollow microspheres and ferroferricoxide magnetic particles are improved favorably by means of high-temperature mechanical ball milling, inclusion of a magnesium liquid can be reduced by means of ultrasonic coupling, stirring and self-regulating treatment, the tissue uniformity is improved, and the target positioning ability is improved. The infiltration ability can be further improved by means of graded temperature-changing hot pressing, and the casting defects are reduced and the crystal grains are refined. Under the action of ultrasonic coupling, stirring and self-regulating treatment and graded temperature-changing infiltrating and hot press molding, the strength and toughness of the magnesium-based composite material can be improved obviously.